Commit e4f323a8 authored by Lars Ingebrigtsen's avatar Lars Ingebrigtsen
Browse files

Add json-available-p

* doc/lispref/text.texi (Parsing JSON): Document it.
* lisp/subr.el (json-available-p): New function (bug#49660).
parent 654ef060
Pipeline #11511 failed with stages
in 44 seconds
......@@ -5301,11 +5301,20 @@ represents @code{@{@}}, the empty JSON object; not @code{null},
@code{false}, or an empty array, all of which are different JSON
values.
@defun json-available-p
This predicate returns non-@code{nil} is Emacs has been built with
@acronym{JSON} support, and the library is available on the current
system.
@end defun
If some Lisp object can't be represented in JSON, the serialization
functions will signal an error of type @code{wrong-type-argument}.
The parsing functions can also signal the following errors:
@table @code
@item json-unavailable
Signaled when the parsing library isn't available.
@item json-end-of-file
Signaled when encountering a premature end of the input text.
......
......@@ -2024,6 +2024,27 @@ used instead. Uses of 'json-encode-list' should be changed to call
one of 'json-encode', 'json-encode-alist', 'json-encode-plist', or
'json-encode-array' instead.
** json.c
+++
*** New function 'json-available-p'.
This predicate returns non-nil if Emacs is built with libjansson
support, and it is available on the current system.
+++
*** Native JSON functions now signal an error if libjansson is unavailable.
This affects 'json-serialize', 'json-insert', 'json-parse-srtring',
and 'json-parse-buffer'. This can happen if Emacs was compiled with
libjansson, but the DLL cannot be found and/or loaded by Emacs at run
time. Previously, Emacs would display a message and return nil in
these cases.
*** The JSON functions 'json-serialize', 'json-insert',
'json-parse-string', and 'json-parse-buffer' now implement some of the
semantics of RFC 8259 instead of the earlier RFC 4627. In particular,
these functions now accept top-level JSON values that are neither
arrays nor objects.
** xml.el
*** XML serialization functions now reject invalid characters.
......@@ -3473,12 +3494,6 @@ locales. They are also available as aliases 'ebcdic-cp-*' (e.g.,
'cp278' for 'ibm278'). There are also new charsets 'ibm2xx' to
support these coding-systems.
** The JSON functions 'json-serialize', 'json-insert',
'json-parse-string', and 'json-parse-buffer' now implement some of the
semantics of RFC 8259 instead of the earlier RFC 4627. In particular,
these functions now accept top-level JSON values that are neither
arrays nor objects.
---
** 'while-no-input-ignore-events' accepts more special events.
The special events 'dbus-event' and 'file-notify' are now ignored in
......@@ -3538,14 +3553,6 @@ To turn this on, set the variable 'w32-use-native-image-API' to a
non-nil value. Please report any bugs you find while using the native
image API via 'M-x report-emacs-bug'.
---
** Native JSON functions now signal an error if libjansson is unavailable.
This affects 'json-serialize', 'json-insert', 'json-parse-srtring',
and 'json-parse-buffer'. This can happen if Emacs was compiled with
libjansson, but the DLL cannot be found and/or loaded by Emacs at run
time. Previously, Emacs would display a message and return nil in
these cases.
---
** The user option 'make-pointer-invisible' is now honored on macOS.
......
......@@ -6311,4 +6311,12 @@ of fill.el (for example `fill-region')."
This is intended for internal use only."
(internal--fill-string-single-line (apply #'format string objects)))
(defun json-available-p ()
"Return non-nil if Emacs is has libjansson support."
(and (fboundp 'json-serialize)
(condition-case nil
(json-serialize t)
(:success t)
(json-unavailable nil))))
;;; subr.el ends here
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